Unlocking the sensing and scavenging potential of Sc2CO2 and Sc2CO2/TMD heterostructures for phosgene detection†
Abstract
The detection of phosgene is critically important owing to its extreme toxicity and potential use as a chemical warfare agent to ensure public safety and security. Two-dimensional (2D) scandium carbide MXenes (Sc2CTx; T = O−, x = 2) stand out as promising materials for gas sensing applications owing to their unique electronic and adsorption properties. In this study, first-principles calculations based on the GGA-PBE functional were employed to investigate the structural, electronic, and mechanical characteristics of Sc2CO2 with different surface termination positions. The adsorption behavior of Sc2CO2 was systematically explored for various gas molecules, including N2, O2, CO, NO, CH4, H2S, and, notably, phosgene (COCl2). Specifically, phosgene exhibited a high adsorption energy, highlighting the selectivity of Sc2CO2 towards this toxic gas. Furthermore, the impact of gas adsorption on the electronic structure of Sc2CO2 was investigated. Strategies such as increasing the operating temperatures and forming heterostructures with transition metal di-chalcogenides (MoSe2 and WSe2) proved to be highly effective to mitigate the challenges related to slow recovery time. Thus, this work underscores the potential of Sc2CO2 MXenes as highly sensitive and selective gas sensors, particularly for phosgene sensing.